Switch for kilns or ovens



June 5, 1951 c. H. STRANGE 2,555,864

SWITCH FOR KILNS 0R OVENS Filed June 18, 1948 INVENTOR. CA/ARL 55 M 577% N65 BY m 6m Patented June 5, 1951 SWITCH FOR KILNS R OVENS Charles H. Strange, White Plains, N. Y., asslgnor to Elsa Lolita Strange, White Plains, N. Y.

Application June 18, 1948, Serial No. 33,796 2 Claims. (01. 200-442) This invention relates to a new and useful improvement in the cut-01f or a signal switch for akiln or high temperature oven such as is utilized for baking ceramics, enamels, heat treating, and the like.

Thus a main object of this invention is to provide a means of automatically shutting off the heat supply to a kiln when a predetermined desired temperature has been attained.

There are devices now being used and known to the art which are operated electrically by means of thermocouples which actuate switches, valves or other means for shutting off the heat supply to the kiln. However, many operators of kilns, especially in the ceramic field. do not consider the thermocouple reliable enough to depend upon, and, therefore, install in the kiln pyrometric cones, which they consider more accurate; in addition to the thermocouple. In this invention a pyrometric cone is utilized for operating the cut-off switch.

In some industries utilizing kilns the working temperatures for certain materials are critical, a few degrees below or above the desired temperature being the deciding factor for success or failure in attaining the desired results.

Many kiln operators will not rely upon electrical thermocouple pyrometers for ascertaining the temperature of the firing chamber. They may use the thermocouple pyrometer for observing the time rate of heating only; and then rely upon the desired critical temperature by means of pyrometric cones, which are slender elongated triangular shaped pieces of clay material that become plastic or yielding and bend over or melt at a certain temperature and this condition is observed by the kiln operator through a peep or spy hole in the kiln wall, generally in the door to the kiln.

A further and important object of the invention is to utilize a pyrometric cone as the means of actuating the device for shutting the heat supply from a kiln, or operate a Warning signal.

The present invention utilizes the collapse or melting of a pyrometric cone to actuate an electric switch, which then energizes a warning signal such as a bell or light, or an electric device which will shut off the heat supply to the kiln.

A still further object of the invention is to provide a cheap and simple means for shutting off a kiln which can be applied to the usual kiln without the use of tools or without altering the design of the kiln or interfering with the customary use of the kiln by the operator.

Other objects and advantages of the invention will be set forth hereinafter or be obvious herefrom, or may be learned by practice with the invention, as realized and attained by means of the instrumentalities and combinations pointed out in the appended claims.

With the above and other objects in View, this invention consists of the novel features of construction, combination and arrangement of parts, hereinafter fully described, claimed and illustrated in the accompanying drawing forming part of this application, and in which similar characters of reference indicate corresponding parts in all views, and in which the drawing shows an illustration of my device, partly in section and partly in elevation.

In the invention depending on the collapse of the cone for mechanical movement of the members as shown in the drawing, the cone may be employed in erect position so that the collapsing temperatures are very near those encountered in conventional practice. The form as shown in said figure comprises a base 40 adapted to be held against the kiln wall by magnets 4| secured to the base. A tube 42 has the outer end secured to the base and has a thin extension l8 of strip or wire material with means such as the cup 2| for supporting the base of the erect pyrometric cone 22. A long light-weight wire lever 44 passing through the tube 42 and base 40 is provided with a ring 45 on the inner end and has a retainer 46 adapted to engage the apex of the cone. The wire lever 44 passes through a pivoted pintle rod 48 and is adjustably secured thereto by a set screw 49. The outer end of the lever 44 is bent downwardly as at 50 and provided with threads 5| to receive thereon a conical cam 52 which engages a roller 54 on the lever B of a microswitch 9. The pintle 48 may be suitably mounted On the base as by a bracket 55. If an asbestos pad such as at 56 is disposed on the inner face of the base for a distance of about an inch from the tube 42 the base may be safely made of brass sheet less than inch thick.

In operation the wire lever 44 is lifted at its inner end and a cone secured in the holder 2|. The ring 45 is then allowed to rest lightly on the cone, as is the retainer 46, the pressure being substantially due to the weight of the lever 44. In the position shown the switch 9 is 01f due to slight pressure on the switch lever B. When the cone collapses, the ring falls removing the pressure on the switch thereby permitting the latter to return to an on position. The cam 52 may be adjusted, or calibrated, so that the switch is actuated at a higher or even lower (due to the pressure on the cone aiding collapsing) temperature than that conventionally designated for the cone.

The invention in its broader aspects is not limited to the specific construction shown and described herein, but departures may be made therefrom within the scope of the accompanying claims without sacrificing its chief advantages.

What I claim as my invention, and desire to secure by Letters Patent of the United States, is:

l. A thermostat cut-off device for kilns and high temperature ovens comprising, in combination, a base adapted to be held against .a wall, a tube mounted in said base, a strip of material extending from said tube, a cup-shaped member mounted at the outer end of said strip, a freely exposed pyrometric cone supported by said member, a lever, consisting of a light-weight wire and passing through said tube and base, a ring upon one end of said wire and adapted to encircle said cone, a retainer, of an angular bend, arranged at the outer end of the wire and engaging the apex of said cone, the other end of said lever being formed with a downward bend, a cam mounted upon the latter, an electric switch, a lever secured to the'latter, and rollers mounted upon said lever and adapted to engage said cam, whereby when the cone becomes yielding from heat, it will automatically actuate the electric switch, whereby to interrupt the current to the heating elements of the kiln.

2. A switching device for a kiln or oven, having a hole in a side wall, a temperature control device comprising a normally vertical plate-like mounting member adapted to be disposed against the outer surface of said wall, a tubular member open through the mounting member and secured d thereto and adapted to be inserted at least partially into said hole, an extension piece forming part of the tube and extending parallel to the latter, said piece being adapted to project through said hole into the kiln, a normally upwardly open cup on the inner end portion of said piece and adapted to hold the base of a pyrometric cone, the cup being open in a direction at right angles to the axis of the tube, a normally horizontal pintle pin mounted on and parallel to the mounting member, a lever mounted on said pin, passing through said tube and adapted to swing in a limited are about the ,aXis of the pin to and from the mouth of the cup, a portion of said lever being adapted to engage a part of a pyrometric cone held in the cup, and switching means secured to the mounting member for engaging said lever.

CHARLES H. STRANGE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,063,012 Cramer May 27, 1913 1,490,408 'Van Aller Apr. 15, 1924 1,981,484 Werring Nov. 20, 1934 2,023,377 Werring Dec. 3, 1935- 2,066,632 Lovekin et a1 Jan, 5, 1937 2,235,766 Knaack Mar, 18, 194 1 2,417,860 Cline Mar. 25, 1947 FOREIGN PATENTS Number Country Date 89,756 Switzerland June 16, 1.921 241,812 Great Brita-in Oct. 29, 1925 

